The Falling Body Model

One particularly famous and very simple model is the equation of a
falling body: the distance d an object falls is proportional to the
square of the time t. If the time is measured in seconds and the
distance in feet, the equation relating these two is

2
d = 16t

This equation is a model of falling objects. It can be used to
predict how long it takes a cannonball to fall from the top of a 200
foot tower (3.5 seconds). This might be important if your product
is designed to drop cannonballs on moving targets.